In present day construction various types of sheet construction materials such as, for example, wallboard, sheet rock, and plywood are used. Standard sizes for sheet construction materials are in the range of four by eight feet or more, making them heavy and difficult to handle. Furthermore, they are vulnerable to damage if not handled with care. Typically, the sheet construction material is manually transported to its final destination, for example, via stairways or inclines and around obstacles in a building.
Various devices for assisting the manual transport of sheet materials have been provided. A first type of such devices comprises simply a bottom support and a handle connected to the bottom support and disposed at predetermined distance above the bottom support. The sheet material is placed on the bottom support and then carried with the handle. Unfortunately, it requires the lifting of the sheet material without the tool on and off the bottom support. Furthermore, it is not suited for stairways or inclines since the sheet material tends to slip off the bottom support when not carried horizontally.
Another type of sheet material carrier comprises three rods attached perpendicular to a flat member with the three rods forming a straight line or a “V” shape. The sheet material is hold between two of the three rods and the third rod is used as the handle. This type of sheet material carrier has various disadvantages such as: pulling unevenly on the panel, tending to slip with heavier materials; and, tending to slip when used on stairways.
The Gorilla Gripper™ holds the top of the sheet material between two flat metal plates when the handle is lifted, squeezing harder when the sheet material is heavier. Unfortunately, the Gorilla Gripper™ has the tendency to release the sheet material if it touches the ground when in use, making it unsuitable for use on stairways and uneven terrain.
Another type of sheet material carrier comprises two opposing cams or one cam and an opposing surface for holding the sheet material there between, as disclosed, for example, in U.S. Pat. No. 4,013,202 (Russo) and U.S. Pat. No. 4,349,225 (Collins et al.). As the device is lifted the cams rotate towards the sheet material thus gripping it. A disadvantage of this type of sheet material carrier is that the cams are slid over the sheet material to engage and disengage it, causing wear on the non-slip coating of the cams as well as on the sheet material. Furthermore, the two opposing cams or the one cam and the opposing surface are disposed having a fixed distance there between, i.e. enabling proper gripping of sheet material within a very limited range of thickness.